Torque amplifier



July 11, 1950 5, HUGHES ET AL 2,515,042

TORQUE AMPLIFIER Filed Feb. 8, 1946 INVENTORS ERNEST S. HUGHES VAUGHN L. AGY RICHARD J. DUFFiN Attorney Patented July 11, 1950 TORQUE AMPLIFIER Ernest S. Hughes, Vestal, and Vaughn L. Agy, Queens Village, N. Y., and Richard J. Duffin,- Washington, D. 0., assignors to the United- States of America as represented byv the Scoretary of the Navy- .Application February 8, 1946, Serial No. 646,444

1 This invention relates to a torque amplifier or servo-system f or converting rotation at low torque to equivalent rotation at higher torque or for following. a rotating element of low torque and producing a corresponding rotation capable of a certain amount of useful work.

An object of the invention is to control the speed of rotation of an electric motor so that it faithfully represents a value at an increased power or torque.

Less comprehensive objects are included, as will be apparent from the following disclosure.

In many instances it is desirable to enable a certain rotation to be reproduced or followed, as where the rotation of a controlling shaft indicative of a condition or value is of such low power as to be incapable of giving a useful result. For example, a propeller type log to be towed in the water behind a Vessel rotates at a speed varying with the peed of the vessel through the water. If a load be placed upon the propeller, it will be caused to drag and thus to rotate at a slower speed than it should and therefore it is impossible to cause it to give a direct record of its operation, as by operating a train of gears in a recording mechanism. In this case it is desirable to pro vide a means operating at a speed directly proportional to the speed of the unloaded propeller but capable of any required amount of work, such as operating recording and/or indicating mechanism. It is such a device that is the subject of this invention.

It is contemplated that the propeller of the instance cited is capable of making and breaking contact in an electrical circuit of low voltage and current and at a frequency directly proportional to its rate of rotation.

Alternatively, the device to be described may be used to provide a rotation proportional to the frequency of electrical impulses received, even though no rotation is directly represented thereby.

The single figure of the drawing is a diagrammatic sketch illustrative of the invention.

In the drawing, l is a sensitive relay for receiving electrical signals. Relay l controls the operation of an electromagnet 2, the electromagnet being activated whenever the sensitive relay closes its circuit. A pivoted ratchet 3 operates step-wise a ratchet wheel 4 which is secured against opposite rotation by a detent 5. The arrangement is such that electrical impulses in the relay i will result in step-by-step rotation of ratchet wheel 4 in a single direction.

Secured to and rotating with ratchet-wheel 4 1 Claim. (Cl. 318-1 73) is a lever 5 slotted at l for operation of a crank 8. Crank arm 9 is rotatably mounted on a shaft H andhas a projection in electrical contact with a circular resistance wire coil l0 secured to shaft 1 l. Elements 9 and it constitute a rheostat. Also secured to shaft H are collector rings l2 contacted by wipers IS. a gear train hi by a motor l5 which provides the direct output of the device.

By means of wipers l3, collector rings 12, and suitable connections shown, rheostat 9-H] is placed in the armature circuit of the motor l5, and thus will affect the speed of the motor. At Hi there is shown a tachometer for indicating the speed of the motor.

Since resistance in the armature circuit may be varied by relative motion between 9 and I, there is provided a means whereby the motor speed is controlled in accordance with the rate of the incoming electrical impulses. Vibration of the electromagnet 2 will cause arm 9 to advance over resistance wire H). In the preferred embodiment, this results in decreasing the resistance in the armature circuit and a consequent increase in speed of the motor l5. However, increased speed of the motor tends to rotate resistance wire It in such direction as to slow the motor. A point will be reached where the speed of the motor is exactly equivalent to the rate of incoming signals.

In operation, assuming rotation of the motor is and incoming signals to the relay l, the system will be rotating smoothly, and the shafts rotating at the same speed. If signals begin coming in at an increased rate operation of ratchet-wheel 4 will cause crank 9 to move over the resistor in such a direction as to decrease resistance in the armature circuit of the motor Hi. This will resuit in a speeding of said motor, by which action the resistor ID will be brought up to the same speed as the arm 9 is rotating. oppositely, a slowing of the signals will result in a slowing of the motor.

Numerous changes in detail are contemplated. If the incoming signal may be of sufficient strength directly to operate the ratchet magnet 2, the sensitive relay I may be omitted. A further modification is possible in that the motor speed might be controlled by a rheostat in its field circuit, rather than in the armature circuit as shown. In this case it would be arranged so that it will operate oppositely from the arrangement shown, i. e. an increase in resistance would cause the motor to operate at a higher speed.

Tachometer I6 is shown merely for an example Shaft l l is operated through 3 of the ways in which the output of the motor may be employed, and forms no essential part of the combination. Another example would be a total distance recording device, or other record-making or indicating instrument pertinent to the value represented by the incoming electrical impulses, or rotation In case a controlling shaft is capable of sufiicient output to operate the rheostat directly, all mechanism to the left of the crank' arm 6 may be omitted.

We claim:

In a device for operating an electric motor at a speed controlled by the repetition rate of a series of electrical impulses, a first shaft, a radial contact arm mounted on said shaft, a ratchet wheel mounted on said shaft, a ratchet pawl associated with said ratchet wheel and adapted to rotate said ratchet wheel one notch at each movement thereof, electro-magnetic means associated with said pawl and adapted to move said pawl, means for energizing said electromagnetic means in response to said electrical impulses, a direct current electric motor, a second shaft driven by said electric motor coaxially positioned adjacent said first shaft, a toric resistance element carried by said second shaft and in electrical contact with said electrical impulses.

ERNEST S. HUGHES.

VAUGHN L. AG-Y.

RICHARD J. DUFFIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,506,765 Merrill Sept. 2, 1924 1,521,824 Merrill Jan. 6, 1925 2,075,103 Edwards et a1. Mar. 30, 1937 FOREIGN PATENTS Number Country Date 449,616 Great Britain June 30, 1936 

